A Novel Cell Traction Force Microscopy to Study Multi-Cellular System
Figure 6
Comparison of mixed-boundary condition method and full-field displacement boundary condition method.
(a) Phase contrast picture of a single cell cluster to be studied. Scale bar: 50 µm. (b) The displacement field generated by cell cluster on the top surface of substrate. (c-e) The traction field calculated by mixed-boundary method, and full-field displacement boundary method (with iterative calculation 1 time and 2 times, respectively), were shown respectively. The difference of RMS of the traction between mixed-boundary method and full-field displacement boundary method with 1 time iteration was 1.6×10−1 kPa, less than 3.8% of the maximum computed traction at cell cluster and substrate interface. The difference of RMS of their nodal force was 0.2 nN, which was 0.25% of the maximum nodal force at cell cluster and substrate interface. Dashed lines in orange outline the cells boundaries. (f-g) Histograms of nodal traction and force obtained by the two methods demonstrated good agreement between each other. (h) Sum of net forces and absolute forces calculated by the above three conditions. The force equilibrium was best satisfied in mixed boundary condition method, which is 6.69% of total force. (i) Sum of surface nodal force distribution calculated by above three conditions. The RMS results of nodal force calculated by mixed BC method and 1-time iteration method agreed within 4.96%. (j) Sum of surface nodal traction distribution calculated by the above three conditions. The RMS results of nodal force calculated by mixed BC method and 1-time iteration method agreed within 9.27%.